Electric heating system



Sept. 4, 1928. 1,683,196

L. A. KEMPTON ELECTRIC HEATING ,SYSTEM Filed NOV. 17, 1927 lnve-tor`:Leslie A. Kemp-ton,

Patented Sept. 4, 1928.

UNITED STATES 1,683,196 PATENT oFFicE.

LESLIE' A. KEMPTCN', 0E BRIDGEPORT, CONNECTICUT, AssTGNoR To GENERALELEC- TRIC COMPANY, A CORPORATION or NEwYoRK.

ELECTRIC HEATING SYSTEM.

Appiicafion. inea November i7, i927. seriai No. 233,968.

l My invention relates to electric heating systems, inoie particularlyto three-wire electric heating systems, and ha's for its object theprovision of simple and reliable means for making the electricalconnections for various rate'sof heat generation.

My invention relates more especially ,to

electric heating systems in which a three-Y wire supply source is usedhavingtwice the voltage between the two outside wires as between eachoutside wire and the middle or .neutral wire, for example, 22() voltsbetween the two outside wires and 110 volts between each outside wireand the neutral. In the operation of electrical apparatus on athree-wire circuit of this character, it is desirable to connect theload across the. two4 outside wires as far as possible so as to balancethe load on the circuit. In apparatus iii which a plurality of heats areprovided, i. e., a pluralityv of diiierent rates of heat generation,lthe connections may be arranged so that the .heating lresistor isconnected across the' two outside wires to give the high heat, whereasthe lower heat' or heats may beA obtained by connecting the resistor toone side only of thev supply source. Inma-king the connections for threeheats, for example, i. e., high, nicdium and low heats, the heatingresistor may be divided into sections whereby one or both of thesections may -be"uti1ized. For high heat the two sections may'lbeconnected in series across the two outside wires, for medium heat one.section maybe connected l across one outside wire and neutral, and

for low heat the two sections may be connected in series across oneoutside wire and neutral.

In accordance with my invention I provide simple and reliable means forcarrying out the aforesaid connections for the three heats comprisingtwo suitable rotatable contact members which are operated together andarranged to cooperate with suitable. stationary contacts. The stationarycontacts are electrically connected to the heating resistor and to thethree electrical supply wires.

For a more complete-understanding vof my invention reference should behad to the acompanying drawing in which Fig. 1 is a sectional view ofmeans for carrying out the various connectionsln accordance with myinvention; Fig. 2 is a :Era mentary plan view -of the device shownin.ig. 1; Fig. 3 is a sectional v iew taken along the line of Fig. 1looking in the direction of the arrows;

Fig. 4 is a fragmentary perspective view such as a phenolic)condensation product.

This Abase is circular in iorm and has a tu-.

bular metallic member 11 embedded in it and' extending centrally throughit, this member forming a bearing for an operating shaft 12 carrying twoelectrical contact members 13 and 14 which are rotatably mounted on theshaft in electrically insulating relation with respect to the shaft andwith respect to each other. As shown, the rotatable contacts 13 and 14are 4mounted on polygonal electrically insulating blocks 15 and 16, thecontact members being provided with polygonal 'apertures which tit onthe blocks.l in turn secured to a poylgonal metallic hub 17 providedwith a central bore in which the shaft 12 is free to turn. vBarrierdiscs 18 made of insulating material are provided on each side andbetween the contact members 13 and 14.

A suitable driving connection is providedv between the shaft 12 and thehub 17 whereby the hub is turned with a snap action from one position toanother. As shown a metal plate 11a is embedded in the base 10 andfurther secured to the base by riveting the journal member 11 oin -toit. This plate 11a is provided with four'projections 19 which areequally spaced around the axis of the shaft 12 and act as stops todefine four positions of the members 13 and 14. A specially shaped pawl20 is provided having a portion which fits between a pair ofprojections19 and providedl also with a bore in which fits-an eccentric cam member21 secured to .the shaft 12. This pawl 2O has a projection 22 at its endwhich ts in a radial slot in The blocks are 2, nasales member 23 which tin slots in a metallic with-the variousfstationary contacts. 'Thememberv 241Y provided with an octagonal bore stationary contacts mayalso be considered as itti'ng on the hub. A spiral spring 25 is beingarranged in two groups with which the also provided surrounding shaft 12and havmembers 13 and 14 cooperate respectively,l ing its ends bentlaterally so as to terminate' member 13 cooperating with av groupcom- 70intwo parallel portions 26 and 27. These prising the three stationarycontacts 30, 32b portions embrace two vprojections 28 and 29 and 33b andmember l14 cooperating with a hich are secured to the shaft'12 and theVgroup comprising the four, stationary conhub 17 respectivel i tacts 30,31, 323L and 33a. y

AS thus arranged, it will be observed that Referring to Figs. 5 -8inclusive, the. elec- 75 when the shaft 12'is turned by knob 12'JL intric heating resistor,'which, for example, either direction, the springis compressed by may be a hot `plate or oven heating unit of.,

' the engagement of the projection 28 with it an electric range, isprovided with an interand a force thereby applied to the hub mediateconnection pointJ or tap 35 wherebyA through the agency of theprojection 27. At it is divided into sections 36- and 37. As 80 the sametime the pawl 2O is withdrawn from shown the tap 35 is in the center sothat the between the projections 19. by the turning l' sections 36 and37 have equal resistance's,

of' the cam 21, and when the shaft 12 has -although obviously the 'tapmay be `at some been turned approximately '90 the pawl will other pointwhereby the sections are of .r

. be withdrawn sufficiently to clear theprojecunequal resistances, ifdesired. The central 35 tion 19 against which it is pressed by the point35 is electrically connected toy the'con-4 spring, and it will then snapinto the space tact 31, one of the outside terminals, as between thenext two projections' 19. In' shown theoutside terminaljofsec'tion36,'.is

' this manner Ithe contact members 13 and 14 connected tothe'contact32", while-the other v fare snapped from one position toanother. outside terminal isconnected to the station-` 9 l The contactmember 13 is provided with a tary contacts 33EL and 331. The neutral.wire

relatively long radial contacting projection of the three-wire supplysource 38, shown or arm 13a (Fig. 5), a relatively short proas themiddle wire, is co ectedV to the stajection 13h situated diametricallyopposite tionary contact 32a, while the two outside 3 the projection13', and with a shorter radial wires are connected respectivelyto thesta- 9E contact projection 13 at right angles thereto. tionary contacts30a and 30". n The contact member 14 is rovided with a With theconnections previously described,

. single relatively long radialJ contact projec- Awhen the switch is.turned to the position .tion 14a and witli two shorter projections shownin Fig. 5, i. e., the members 13 and 14 3 5 14,7 'and '14 at rightangles to projection 14EL turned to the positions indicated, the heating1( l and diametrically opposite each other. The resistor is disconnectedfrom the supply:

' vvtwo members 13 and 14 are secured to the source,this position beingthe oil posit-ion;v

'hub 17 so as to rotate in parallelplanes but- For high heat, i. e.highest rate of heat gen-I with' ai 90"4 displacement, 1. e., with theconeration, the switch is turned to the 'next 40" tact projection 13extendin'g at right angles position in a clockwise direction which Ais 1with the projection 148%, as shown in Fig. 5. shown in Fig. 6, wherebyit will be observed Sets of stationary contacts 30, 31, 32, and that thetwo ends of the resistor are con- 33 (Fig. 2) are secured to the basemember nected throughIl the two. switch members 13 in (position to beengaged by the members 13 and=14, respectively,"to the outside wires oft an 14 in their. four positions, these stationthe supply source. Thisconnects the twol `1A ary contacts being eglually spaced at 90 sectionsof the resistor in series across thet angles on the base T e set 30comprises an higher voltage wires of the supply source, l

upper'short contact 30 and alower long conno connection with the centraltap 35 being l tact 30",*-the set31 comprises a single short provided.For medium heatthe switchis upper contact, while the /set 32 comprisesan turned in a clockwise direction to the next 1 -upper long contact32a` and a lower long' position, as indicated inF ig. @whereby the\c0ntact 32. 4 The set 33 comprises an upper central tap 35 is connectedthrough. the -long contact 33a and a lower short contact switch member14 to the neutral wire, and 33"; It will be understood that the 'lowerthe outside terminal of the section 37 is 4constationary contacts areengaged by lthe .rotatnected through the switch member 13'to one 1 ablecontact 'member 13, whilethe upper of the outsi e wires of thesupplysource.

' stationary contacts are engaged -by Vthe con- This connects thesection 37.l acrossone side tact member 14 the short stationar contactsof the supply source, thesection 36 being being engaged y the longrota-tab e'contact deenergized. For low -he'at the s'witch is 0.1projections, and vice versa. In the sets 30 turned in aclockwise'direction to its next l and 32 e contacts are electricallyinsulated position in whichi one end of the resistor is from eaother,but the two contacts of the. connected through the member 13 toset 33 are .electrically connected together. oneoutside wire and theother endof the Suitable binding screws 34 are frovided resistor isconnected through the g switch u whiereby electrical connections maylbemade member 14 to the neutral wire. This donneel tion puts the twovsections in seriesl across one side of the supply source. l

It should `be noted that the rotating contact member 13 serves thepurpose of connecting one end of the resistor to one of the outsidewires .in all three of the operating positions. rThe same end of theresistor is connected in thehigh and low heat connections, while for themedium heat connection the opposite end of the resistor 'is connected.The, rotary contact member 14; serves the purpose of making theconnections for the remaining outside wire and the neutral wlre.For-high .heat it-will be observed that thls contact member connects oneend` of the resistor to one outside wire, for medium heat it connectsthe central point to the neutral wire, and for low heat it connects oneend of the resistor to the neutral wire.

In the. modified form of my invention shown in Fig. 9, the electricalconnection between t-he Contact 33b and the contact 33a is eliminatedand in place thereof a connection is provided between the contact 33band the contact 32h.- Vith this arrangement'the connections for theresistor are the same as previously.I described in 'connection with Figs..5 to 8 inclusive, with the exception that on the medium heatconnection shown lin Fig. 7 the reverse end of the resistor as comparedwith- Fig. 7 is connected to one outside wire. This energizes section 36of the resistor instead of section 37, as shown in Fig.' 7. This will beunderstood with reference to Fig. 7'. In Vother words, with the`connections shown in Fig. 9 the switch blade 13 connects the same endofthe resistor to the same outside wire for all three heats, this end oflthe resistor being that end whichis shown connected by the switch blade13 in Figs. 6 and` 8.

While I have described my invention as embodied in concrete form and asoperating in a specific manner in accordance with the provisions of thepatent statutes, it'

should be understoodl that I do not limit my invention thereto sinceVarious modifications thereof will i suggest themselves to those skilledin the art without departing from the spirit of my invent-ion, the scopeof which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. The combination with a heating resistor provided with an intermediateconnection point, of a supply source provided with two outside wires anda neutral wire, a switching member for connecting one end of saidresistor to one of said outside wires in any one of three positions, anda seco-nd switching member for controlling the connections from saidintermediate point and one end of said resistor to said neutral wire andone of said outside' wires in three positions so asto give threedifferent rates of heat generation.

2. The combination with a heating resistor provided with an intermediateconnection point, of a supp source prov1ded wlth two outside wires an aneutral wire, a switching member for connecting one end of said resistorto one of said outside wires in any one of three positions, a secondswitching 'member for cont-rolling the connections from the other .endof said resistor and saidi'ntermediate point to the other outside wireand said neutral -wire iri said three positions so as to givethreedifferent rates of heat generation,

.and means for operating said switching members simultaneously.

3. The combination with a heating resistor provided with an intermediateconnection point, of a supply source' provided with two outside wires'and a neutral wire, a rotary switching member for connecting one end ofsaid resistor to one of said outside wires in any oneof three positions,a second switching member for controlling the connections from saidintermediatepointand o-ne end of said resistor to said neutral wire andone of said outside wires in said three positions so as to give threedifferent rates of heat gen' eration, and means for operating saidswitching member simultaneously from one position to another.

,4. The combination with a heating resistor provided with anintermediate connection. point, of a supply source provided with two.outside wires' and a neutral wire, two rotary l,outside wires and aneutral wire, switching means for controlling the connections of saidreslstor to such supplysource comprising -a group of three stationarycontacts connected respectively to thev two ends of said resistor 1 andone of said outside wires, a rotary contact member cooperating with saidstationary contacts in any one of three positions so as to 'connectoneend of said resistor to said. outside wire, a second group of fourstationary contacts connected, respectively, to said intermediate point,one end. of said resistor,. said neutral wire, and the remaining outsidewire, a second rotary contact member arranged to cooperate with saidsecond group of stationary cont-acts in any one of three positions so asto connect one end of 'said resistor to one outside wire for high heat,said intermediate point to said neutral wire for medium heat, and oneend of, said resistor to said neutral point for low heat, and means foroperating said rotary contact members simultaneously.

6. "The combinationV with a heating resistor provided with anintermediate connectiony point, of a` three wire source of powersupswitching means for controlling the conv ber'seach provided withthree contacts having anv angular arrangement corresponding -to theangular spacing of said stationary contacts, electrical connectionsbetween the ends' of said resistor-and two contactsl in saidglirst grouprespectively, an electrical connection between the third contact of saidfirst group and an, outside wire of said supply source, electrical'connections respectively between .twov of the stationary contacts 1nsaid second group and said intermediate point and the neutral w'ire ofsaid supply source,A an electrical connection between one end of saidresistor and another stationary contactv in said second group, and anelectrical connection between the fourth contact in saidsecond group andthe remaining out-v side supply wire, and means'for operating saidrotary contact members simultaneously to various positions to givevarious heats, whereby for high .heat thel ends of said resistor areconnected to the outside wires of saidrsupplyV source by said rotanycontacts, respectively, for medium heat one end of said resistor isconnected to one outside wire by said first rotary contact and saidinterme-l diate point is connected to the neutral wire by saidsecondrotary contact, and for low heat one end of said resistor is connectedto one of said outside wires by saidfirst rotary Contact and the otherendof said resistor is connected to said neutral wire by said secondrotary contact- In witness whereof, I have hereunto set my hand-this12th day of November, 1927.

LESLIE A. KEMPTON.

